docs: def path2url(p):
      """ Return file:// URL from a filename.
      """
      # Python 3 is a bit different and does a better job.
      if sys.version_info.major >= 3 and sys.version_info.minor >= 4:
          import pathlib
          return pathlib.Path(p).as_uri()
      else:
          return six.moves.urllib.parse.urljoin(
              'file:', six.moves.urllib.request.pathname2url(p)
          )